Fire can be a radiant experience of heat, warm and pleasure or it can become a nightmare of horrific pops, violent sparkling and explosions. Can firewood actually explode?
Of course there’s always going to be a certain amount of crackling and popping because of fire’s nature with wood, but you can expect that your firewood will not explode.
There are two main reason why this happens. Either the wood wasn’t properly dried or it contains resin. But we can control the more dangerous aspects that have the potential to create havoc in what should be a lovely experience.
What Does It Mean When Firewood Pops and Crackles?
When wood burns, a chemical reaction occurs called “combustion.” Wood contains cellulose that reacts to oxygen, resulting in heat. When crackling and popping seems beyond normalcy, this could be a sign of low combustibility, also called low combustion efficiency.
This means the least amount of matter converts into heat that spews particulate matter, scalding-hot projectiles and black, thick smoke. The wood’s saturation determines the amount of sparking because, as the wood heats up, the moisture turns into steam. This increases pressure, forcing it to explode.
What Causes Firewood to Pop?
Any moisture in the wood will create popping. Even though it may appear dry, there could be water stuck inside the pores. This is because trees have a natural propensity to absorb water. Water restricts the wood’s combustibility which results in popping.
High-resin woods will almost always pop in a fire. This is because resins create a seal. As they heat up, they expand and fill crevices. If there’s moisture compounding the seal, it will explode. Limit using resinous woods by relegating them for kindling or in a mixture of hardwood and softwood.
What Types of Wood Are Most Liable to Pop and Explode?
Red cedar and poplar have very flammable saps that explode in a fire, this includes conifers and pines. Resin is present when you see amber-colored sap globules dried onto the wood.
Saturated wood develops moisture pockets that become compressed bubbles of gas when set alight. They’ll explode like the 4th of July, jolting debris everywhere.
How Do You Reduce Sparking, Cracking and Popping?
Drying the wood by air or with a kiln is the best way to prevent crackling. A kiln exposes the wood to heat to release moisture without burning it. This makes for ideal firewood that burns cleaner while reducing explosions, cracks and pops.
Air-dried wood takes much longer and not as reliable as kiln-dried. Also, bigger fires reduce popping and sparking.
Where Should You Store Firewood to Keep It Dry?
Always store firewood in a dry area. Build a structure, purchase a rack or cover it, depending on where you keep it and the climate you’re in.
The easiest way to store your firewood is with a firewood log rack like this one by Woodhaven. Its structural integrity is very sound, and will keep your firewood off of the ground. It also comes with its own cover that will cover the top 12″ of your firewood.
Outdoor Versus Indoor
Always cover firewood stored outdoors with an awning, roof or tarp or the wood will result in eventual wood saturation. This is true even if it doesn’t rain, because humidity is always present.
Constant humidity will dampen wood, leading to unwanted cracking and popping. Make sure it sits at least two inches from the ground to prevent moisture along with bugs and other critters. If you can, store wood inside your house with a basic metal rack, especially if it’s kiln-dried. But avoid storing it in humid areas like the basement or crawlspace.
What Types of Wood Are Good to Use in a Fire?
In general, hardwoods are the best because they’re least likely to crackle. Hardwood holds less moisture with a higher heat output. Hardwoods burn longer than softwood and maintain a low, consistent flame.
The coals glow longer but more difficult to light than softwood. Hardwood is excellent for indoor fireplaces and wood-burning stoves.
Softwood contains more resin with poor combustibility and coals that lose heat fast. Softwood burns very hot and quick with a high flame, requiring more frequent care and attention. These are best for kindling, campfires and outdoor use.
Which Trees Have the Best Wood for Burning?
Any seasoned, or kiln-dried, wood has a moisture content around 20% which makes it ideal, efficient and safe when burned.
There are some woods that burn well when seasoned, but there are some pitfalls:
- Mulberry – Mulberry is an energy-rich wood, like Oak but it’s hard to burn and always results in excessive sparks and pops, even under the best seasoning treatment.
- Black Locust – Black Locust burns for a very long time with an intense heat and mid-sized flame. But, this wood has thorns, so use caution when handling it. The thorns can also make for some deadly projectiles if the wood is too moist.
- Elm – Some species of Elm stink when you burn them with reports of people having difficulties splitting the wood. When burned in a fire, you must constantly watch it and pay close attention.
- Beech – Beech wood burns very hot but has coals that burn for a long time. The heat produced can melt metal.
Which Trees Should Not Be Used in a Campfire?
Trees that are difficult to cut should avoid being a part of your fire:
- American Elm
- Red Gum
- some species of Oak
- Sweet Gum
Where Should You Buy Firewood?
It cannot be stressed enough that you should only buy local firewood. This will prevent importing foreign pests into your area and don’t move firewood from more than 50 miles away.
If you’ve never experienced a fire with exploding wood, consider yourself lucky. It’s a scary, unexpected event that comes on like a firecracker with coals and embers shooting everywhere. Some going as far as 20 feet away.
Knowing how to handle this problem before building a fire will mitigate hazards that can cause injury and damage. Be smart with wood selections and opt for kiln-dried firewood whenever you can.
Reduce the wood’s moisture by storing it in a dry place free of humidity and rain exposure.